Electric meter



July 25, 1939. M. E. NULsEN Er AL ELECTRIC METER Filed April 30, 1936 2 Sheets-Sheet 1 INVENTORS Maw/n L'/V'ulsefl/ ATTORNEY Jly 25, 1939- M. E. NuLsEN Er A1. 2,167,083

ELECTRIC METER Filed April 30, 1936 2 Sheets-Sheewl 2 ATTORNEY Patented 25, 1939 UNITED STATES. PATENT ori-ICE ELECTRIC METER y Marvin E. Nulsen and Lawrence B. Goetz, In-

dianapoli's, Ind., assignors to P. B.. Mallory & Co., Inc., Indianapolis, Ind., a corporation of Delaware Application April 30, 1936, Serial No. '77,108

11 Claims.

This invention relates to electric meters for the measurement of electric currents and the like.

An object of the invention is improved meter structure.

to produce an Another object is to improve a shadow meter. A further objectis to provide an improved moving coil current indicating meter.

Additional objects are to improve the pivot mountings and damping means for meter armatures.

Other objects of the invention will be apparent from the following description and accompanying drawings taken in connection with the appended claims.

The invention may be embodied in shadow indicating meters such as are used in radio sets and the 'like to indicate, by a visible shadow on an indicator plate, the degree or exactness of tuning of the set to any particular broadcast signal. 'I'he invention may also be embodied'in a moving coil type of meter such as an ammeter-voltmeter for measuring electric currents.

The invention accordingly comprises the features of construction, combination of elements. arrangement of parts, and methods of manufacture referred to above or which will be brought out and exemplified in the disclosure hereinafter set forth, including the illustrations in the drawings, the scope of the invention being indicated in the appended claims.

meter Figure 3 is an end section on the line 3-3 of Figure 2;

Figure 4 is a bottom View of the shadow meter;

Figure 5 is a detail view showing a modified form of spring adjusting mechanism;

Figure 6 is a section on the line 6 6 of Figure 5;

Figure 7 is a face view of a moving coil type of shadow indicating ammeter-voltmeter;;

Figure 8 is a section on the line 8-8 of Figure 7; -Figure 9 is a face view of a moving coil type dial-indicating ammeter-voltmeter;

Figure l0 is a section on the line IG-III of Figure 9;

Figure 11 is a detail view illustrating the damping means;

(crm- Figure 12 is a detail view illustrating the terminal connections for one end of the moving coil; and

Figure 13 is a detail view of a modied form of shadow indicating meter.

Like reference characters denote like parts in the several figures of the drawings.

While a preferred embodiment of the invention is .described herein, it is contemplated that considerable variationv may be made in the method of 10 procedure and the construction of parts without departing from the spirit of the invention. In the following description and in the claims, parts will be identified by specic names for convenience, but they vare intended to be as generic in 15 their application to similar parts as the art will permit.

Shadow meters have been used in the past to indicate proper tuning of radio receivers and have consisted in general of a translucent plate spaced 20 from a slotted screen behind which was disposed a light source, a shadow vane pivotally mounted between the slot in the screen and the translucent plate serving to throw a shadow of variable width on the translucent plate. Control of the shadow 25 vane was usually effected by providing an arma.- ture attached to the shadow vane and a permanent magnet to hold the armature in a normal or no-current position. An electromagnet was associated with the permanent magnet for rotat- 3.0 ing the armature responsive to current of various strength through the winding of the electromagnet. The poles of theA permanent magnet were normally so arranged that when the electromagnet was nqten'rgized the plane of the shadow 35 vane was perpendicular to the screen so that the shadow cast thereon was of minimum width and had the appearance of aline. The electromagnet was so connected into the radio receiver that the DC current through the electromagnet would 40 swing the armature so that the shadow vane caused a broader shadow on the translucent screen. Thus when the switch of the radio receiver was closed the current passing through the electromagnet'would reach a maximum value so that the shadow vane would be deflected the maximum distance and cause a shadow of maximum width. In tuning the radio receiver to a particular broadcast signal, the circuit was so arranged 50 that the current in the electromagnet would decrease as resonance was approached so that with perfect tuning the shadow would again approach its narrowest width where it would have the appearance of a line. 'I'his would indicate to the 55 lternaliyoi thecaseby'bracket Il.

The lamp 2l preferablybas al single short straight.

mament 2l positioned substantially in the plane of the shadow vane when the yvane is in the normal no-current" the metal ease 2l is provided with a recessed corner so that lamp 2i may be mountedex- Lamp Il is provided with a suitable enclosing case 2 5 and this case is preferably blackened both inside and outside to prevent undesirable light reiiections sothattheonlylightwhichpassesintothe shadow meter and on thescreen 22 is that coming directly vfl'llmtbe filament of lamp Il. Electrical terminals 2| and 21 are providedfor connectingthelamplitoaaourceofelectricen- Within the ease Il ismounted electromagnet 2l havingawindingll andapairof poles Il and 8| "having curved faces disposed at opposite positions approximately on the periphery of-a circle. A bracket l! oi non-magnetic material, such as bras or the like. supportselet Il and its pole members ll and li in position and likewise provides pivot supports for the armature-shadow vane assembly 33.

The armature-shadow vane assembly is suitably made from a single piece oi' magnetically permeable sheet metal suchl as iron or steel. Bheetmetal piece issoshapedandtreated as to provideV two hardened points Il and 3l along one edge thereof to serve as pivot points. Pointslland lliitintoapairoispacedeircul'ar conical depressions or loeatingfand pivoting re- II and I1 on a face of mounting bracket Il. Y

In order to hold pivot points Il and within depressions 36 and 31 a portion of sheet metal part I3 `between points and 3l extends out beyondthesepointsandisprovidedwithan eyelet. Asmallcoilspring llha'soneotits ends hooked into eyelet l! rand is held at its other end under tension by atensioning adjustingmechanism Il, parts ll, 4t, I1 and Il, supported on bracket l2.

Apairoi'earsll andllarealsoprovidedas partofsheetmetalmemberandarebentover- .in opposite directionssothat eachis approxikmatelyatrightanglestothemainbodyofsheet member Il. Ears and I! are provided with curvedexterioredgeapositionedjustwithinthe position. For convenience.v

approximate circle denned by the poleV faces ci electromagnet poles il and ll. When the arma'- j ture is in normal or rest position, just 'the tips oi armature ears Il and l2 come opposite the portion oi the pole faces are covered by the outer edges of armature ears-ll and 42. y

The remaining part of sheet metal member u formsla flat shadow vane I3 normally positioned in a vertical plane through the center of the case. A vsmall slot u is provided in the wall of case 2t between lamp filament 2l and vane Il. The illament 23, slot Il, vane 4l and translucent screen 22 are thereby all disposed in a line through the case.

The tension adjusting mechanism for coil spring 39 comprises an adjusting screw I5 positioned in a threaded opening in bracket l2 on the back end of case 20. Screw I5 has its knurled. head 4I on the outside of the case ior manual adjustment purposes. Within vthe case a leaf spring 41 extends across the tip of screw I5 and is loosely held`at its ends inslots Il and provided in bracket non opposite sides of screw y". A clip 50 fits around the central portion of leaf vis spring 41, but is free to slide thereon cup u has a small loop punched up from its outer face for receiving the hooked end oi' coil spring 30u The inner faceA of clip ill is provided with a circular recess or hole'toaccommodate a reducedv end on screw 45. It will be`apparent that the tension of spring 39 can readily .be adjusted by f turning the knurled head 4I of screw 45. Thu

by turning the screw farther into the case. leaf their sockets but likewise lprovides the restoring force necessary to return the vane to normal or zero" position and to react against the force of electromagnet 2l. For further safety an extension Il is provided on i'rame 32, extending through hole 38 so that the armature member will not be knocked out oi' position by any accidental jarring of the instrument. r 1. Y

A modiiied tension adjusting mechanism is shown in Figures 5 and 6 comprising a tubular member l2 having a pair of axial slots 53 cut through itsv wall in diametrically opposed positions and an end wall 54 .at vthe external end thereof is provided with a hole of smaller diameter than the inside of the tubular member, said member l! being secured in a hole in the back of the meter ease at 55. A rod-like adjusting member Il attached to spring v3l and pro-l vided with a pair of opposed wing projections I1 is held within tubular member I3 with its shank portion slidable in the hole in wall Il and its wing portions slidable in'slots 53 and a set screw Il is provided in a threaded hole in the wall of tube l2 for clamping theadjusting member in any position desired. f

Referring to the modified form oi' meter shown a in Figures 7 and 8 the stationary parts include f faces 8l. A cylindrical bridging core 62 of vmagnetic material, such as iron, is supported between the faces 6| by a screw 63 mounted on a bracket 64 oi non-magnetic material, such as brass, so

as to provide a cylindrical slot between faces 16| and the periphery of bridging core 62 wherein armature coil 65 may turn. The armature assembly, of which coil 65 is a part, is pivotally, mounted on a pair of cross braces 66 and |66 rigidly secured in spaced relation to the faces of magnet 59 by screws 61 and insulating rods 68 so that cross braces 66 and |66 are insulated from the magnet and from each other. Cross braces 66 and |66 are each provided with a smooth conical depression 69 and |69, respectively, in' their upper faces with the bottom of the two depressions on a central axial line through cylindrical bridging core 62, this line representing the posi--v tion of the axis about which the armature is pivoted.

The armature assembly comprises a iibre spool 18 upon which armature coil 65-is wound and a pair of supports 1|, 12 of non-magnetic sheet material, such as bronze, riveted, respectively, to the front and back of the spool. Supports 1| and 12 are provided with downwardly extending points 13 and 14, respectively, on their lower edges, said points resting within conical depressions 69 and |69, respectively, to provide the desired pivot support. A portion of support 1| is formed into a shadow vane 15 for casting a shadow indication on an indicating screen in the same manner as is set forth inthe preceding flgures. It is, of course, possible to provide a pointer instead of a shadow vane and a dial plate associated therewith to indicate the deflection of the pointer, as is shown in Figures 9 and 1G.

The armature assembly is held in 'centered position and the points 13, 14 are held within depressions 69 and |69 by a spring assembly comprising a pair of coil springs 16 and 11 each secured at its upper end to the pivoted vcoil supports 1| and 12 below the pivot axis of the armature assembly, and at its lower end to the front and rear ends, respectively, of a lever arm 18. Springs 16 and 11 are insulated from the armature assembly by insulating bushings comprising metal eyelet 19 and insulating ring 88 in members 1| and 12 in a manner similar to that shown more vclearly in Figure 12. Lever arm 18 is pivoted on an adjusting screw 6| which is arranged to slide in a hole in U-shaped bracket 82 below the center of the magnet assembly. Bracket 82 is supported by cross braces 66 and |66 but is insulated from these by insulating layers 86. An adjusting nut 83 is threaded on screw 8| to provide for variably tensioning the two springs 16 and 11.

One end of coil 65 is connected to sheet metal supportf1| and the other end to support 12. The external circuit connections to coil 65 are made through cross braces 66 and |66 and pivot points 13 and 14 and the supports 1| and 12. Circuit arrangements of conventional form are shown in Figure 8 for using the meter as a combined ammeter-voltmeter. Current in the am-4 meter circuit will pass in series through incoming conductor 85, brace 66, point 13, support 1|, coil 65, support 12, point 14, brace. |66 and outgoing conductor 86. Low-resistance shunt 81 will by-pass Ymost of the current, however, as is usual in ammeters. When used as a voltmeter the current will follow the same paththrough the meter but will pass out through outgoing conductor 88 containing high resistance 89; shunt 81 being removed in this instance. A 'I'he meter structure of Figures 1 and 8 can be used for a wide variety of applications in vaddition to that of tuning indicator and ammetervoltmeter. The meter can be used in any position, springs 16, 11 serving to hold points 13, 14 in the positioning recesses.

Referring to Figures 9 and 10 a further modifled meter is shown. Some of the parts are similar to those of the meter illustrated in Figures 7 and 8 and are numbered accordingly. In this modification, however, the armature coil is supported entirely by one non-magnetic sheet metal support member 98 having two pivot points 9| and 92 along its lower edge and being riveted to thie sbre or molded resin spool 93 supporting col Pivot points 9| and 92 rest in conical depressions in a U-shaped supporting frame 96 secured to the magnet frame by bolt 96.

A single tensioning spring 94 is hooked into eyelet 19 which is positioned below the pivotal axis through the points 9| and 92 so as to provide stable equilibrium in the armature in its normal position. Spring 94 is secured at its lower end to the end of an adjusting screw 91 held in an insulating bushing 98 in frame 95 and provided with an adjusting nut 99 for varying the position of the screw and thereby regulating the tension on the spring.

An indicating pointer |88 is secured to the front face of spool 93 and is arranged to move over a scale |8| secured to the face of magnet 59.

One end of coil 65 is soldered or welded to sheet metal support 98 and the other end is soldered or welded to metal eyelet 19 which is'insulated from support 98 by insulating ring 88 (see Figure 12). The external circuit conductors |82 and |83 are secured, respectively, to metal frame member 95 and tensioning screw 91so that the current passing to coil 65 will follow a circuit from conductor |82, through frame 95, points 9| and 92 in parallel support 98, coil 65, eyelet 19, spring 94 and screw 91 to conductor |83.

Figure 11 illustrates a means for obtaining damping of the armature movements so that it will be free from excessive oscillations when changes are made in the current flowing in the armature coil or when the meter is vibrated from external disturbances. A damping medium |84 is placed in the conical depression surrounding point 9|, this medium preferably comprising a pasty plastic substance of internal friction sufficient to apply the necessary drag to the rotation of the armature but insufllcient to prevent the armature to rotate by an amount proportioned to the current iiow through the coil 65. The plastic material 04 should preferably be of such viscosity and consistency as to be substantially non-flowing so that it will stay in place in the depression regardless of the position in which the meter is mounted. Materials which are suitable include 4 conductive substance such as soft greases containing graphiteto increase the conductive path between point 9| and the frame 95.

Figure 13 shows a modication of the struc-rvv ture shown in Figures 9 and 10 wherein a shadow vane |85 is provided as part of the armature 6 canbe used in the other modifications shown and such interchange of details is intended to be part of this disclosure.

It is also possible to modify the structure so that the pivt depressions are made in the arl -mature frame and the pivot points are held by the stationary supporting frame.

The use of pivot points instead of jewel bearings, journal type bearings and the like provides a more economical mounting and avoids many of 1I the' disadvantages of these other types. It has substantially zero frictional hysteresis and the ,support depressions insure accurate positioning of the armature without undesired lateral orv axial motion.

n While the vpresent invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, itis not desired to be limited thereby but it is intendedto cover/the invention broadly within the u spirit and scope of the appended claims.

What is claimed is:

l. An electric meter having an armature member and a pivot member for the armature thereof, one of said members having a depres- 80 sion and the other of said members having a portion of hard material tapered to a point, said point resting in said depression, one of said members'being rotatable relative to the other oi' said members, the axis of said rotation making a sub- 35 stantial angle with the axis'of said tapered portion of the one of said members.

' 2. In an electric meter, a rst member having 4a depression andl a second member of hard material tapered to a point, said point resting in 4o said` depression said second member being rotatable relative to said iirst member, the axis of said rotation making an angle of substantially 90 with the axis of the tapered portion of said second member, and a plastic damping medium g5 in said depression surrounding said point, one

of said members comprising the armature and the other of said members comprising the pivot for the armature of said meter.

3. In an electric meter, an armature member,

50 a supporting 4member therefor, one of said members being provided with a pair of projections each tapered to a point, both of said points hav-- lng substantially the same 'orientation relative to said member upon which they are provided,

55 the other of said members having a pair of tap ered depressions,both of said depressions beingy on the same side thereof and being spaced apart a distance equal to the spacing of said points,l

said points resting in said depressions whereby 00 said armature is adapted to turn about an axis coinciding with a line through said points, the axes of said projections making a substantial angle with said axis of rotation of said armature.

4.An electric meter comprising an armature 05 member, a supporting member therefor, said arf mature member being provided with a pair o! pointed projections both extending in the same direction with their axes parallel, said Asupporting member having a pair of tapered depressions 7 in one face thereof, both of said depressions facing in the same direction and being spaced apart a distance equal to the spacing of said points, said points resting in said depressions, an indicator attached to said armature,y and a spring n member arranged so as to hold said points in that many of the details and said depressions and to supply a restoring force to said indicator. 1 y

5. In an electric meter, an armature member, a supporting member therefor. said armaturemember being provided with a pair of pointed projections both extending in the same direction with their axes parallel, said supporting member having a pair of tapered depressions in one face thereof both said depressions facing in the same direction and being spaced apart a distance equal to the spacing of said projections, said projections resting in said depressions, an armature coil mounted on said armature, a -pair of lead-in conductors for said -meter connected to the two parts of said supporting member having said two depressions, respectively, means insulating said parts from eachother, means insulating said pointsifrom each other, the ends of said coil being connected, respectively, to said projections, whereby said lead-in conductors are connected to the ends of said coil through the ivots yformed by said projections and depres- 6. An electric meter comprising an armature member, an electric coil mounted thereon, a support member for said armature member, af de- I pression in one of said members and a point on the other of said members resting in said depression, said armature member and associated coil being rotatable about an 'axis through said `point, a tensioning spring connected at one of its ends to said support and at the other of its ends to said armature and being arranged so as to hold said point in said depression and to hold said armature normally in "zero position. f

' 7. An electric meter comprising an armaturel member, an electric coil mounted thereon, a support member for said armature member,'a depression in one of said members and a point on the other of said members resting in said depression, said armature member and associated coil being rotatable about an axis through said point, a tensioning spring connected at one of its ends to said support and at the other of its ends to said armature and being arranged so as to hold said point in said depression and to hold said armature normally in zero position, a pair of lead-in conductors for said meter, one of said conductors being connected to one end of said coil through said tensioning spring.

8. An electric 4meter comprising an armature member, an electric coil mounted thereon, a support member for said armature member, a depression in one of said members and a point on the otherl of said members resting in said depression, said armature member and associated coil being rotatable about an axis through said point, a tensioning spring connected at one of its ends to said support and at thesotherof its ends to said armature and being arranged so as to hold said point in said depression and to hold said armature normally in "zero position, a pair of 1ead`-in conductors for said member, one of said conductors being connected to one end of said coil through said tensioning spring, the other of said conductors being connected to the other end of said coil through said support member and said point.

9. In an electric meter, an armature member, a supporting member therefor, said armature member being provided with a pair of pointed projections both extending in the same direc tion with their axes parallel, said supporting member having a pair of tapered depressions in one face thereof both said depressions facing in the same direction and being spaced apart a distance equal to the spacing o! said points, said points resting in said depressions, an indicator attached to said armature, and a spring member arranged so as to hold said points in said depressions and to supply a zero bias to said indicator, and means to adjust the tension on said spring to vary the restoring force of said meter.

10. An electric Vmeter comprising an armature member, a support member therefor, said armature member being pivoted on said support member, a helical spring attached at one end to said armature member 'and at the other end to said support member and having its axial line at a substantial angle withv the axis about which said armature member is pivoted, and means for applying a variable ltensioning force to said spring.

'11. An electric meter comprising an armature.

member, a support member therefor, said. armature member being pivoted on said support, a helical spring attached at one end to said armature member and at the other end to said support member 'and having its axial line at a substantial angle with the axis about which said armature member is pivoted, and means for applying a tensioning force to said spring and for varying said tensioning force to vary the restoring force of said meter.

LAWRENCE R. GOE'IZ.. 

